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ISTANBUL - A controversial creationist has offered a multitrillion-dollar challenge to scientists.

Adnan Oktar's "call to all evolutionists" promises "10 trillion Turkish lira to anyone who produces a single intermediate-form fossil demonstrating evolution" - a sum roughly equal to $11.7 trillion.

The Muslim writer, who uses the pen name Harun Yahya, is a fierce critic of "the Darwinist dictatorship" and a popular figure in Turkey, where only a quarter of the population believe in evolution.

The 52-year-old former architecture student claims there are no fossils to support Darwinist theories.

"Not one [fossil] belongs to strange-looking creatures in the course of development of the kind supposed by evolutionists."

However, scientists reject his claims that these fossils do not exist. Dr Kevin Padian at the University of California told the New York Times Oktar "does not have any sense of what we know about how things change through time. If he sees a fossil crab, he says, 'It looks just like a regular crab, there's no evolution.' Extinction does not seem to bother him."

Oktar found fame in 2006 when 10,000 copies of his Atlas Of Creation were distributed worldwide. The 800-page volume illustrated his claims that for millions of years life forms have not developed, supporting his Islamic creationist beliefs.

Richard Dawkins, a British biologist, called the Atlas "preposterous", speaking of "the breathtaking inanity of the content".

Oktar responded: "We could have spoken on a more scientific basis if he had been able to produce an intermediate form fossil capable of confirming evolution."

This month Oktar won a case in a Turkish court claiming that Dawkins' website contained blasphemous and defamatory content. Internet users in Turkey can no longer access the site.